Steam-boiler



' 'set, in the county of Norfolk and State of Masthe following is a specification.

g a longitudinal section of the part marked X.

, length of the part Y. Fromthis construction UNITED STATES PATENT OFFICE.

- STEAM-BOILER.

SPECIFICATION forming part of Letters Patent No. 256,446, dated April 11, 1882.

Application filed April 29, 1881. (No model.)

To all whom it may concern:

Be it known that LDAVID RENSHAW, acitizen of the United States, residing at Gohassachusetts, have invented certain new and useful Improvements in Steam-Boilers, of which My invention is specially an improvement upon marine boilers, and by it I gain an econ omy of space with an economy of fuel over'the boilers at present known to me; and it is more particularly designed as an improvement upon the patent granted to D. Renshaw and G. B. N. Tower, December 18, 1877, No. 198,213.

In the drawiugsI have shown in Figure 1 a cross-section of my boiler in two parts, the one marked Y representing the furnace portion of the boiler and that marked Xthe flue portion. In Fig. 2 I show a partial elevation with a portion of the shell removed, and partial section (longitudinallof'the part marked Y and A represents the outer shell of my boiler, within which are inner shells B, inclosing furnaces, and inner shells G, inclosing flues. The shells B surround furnaces and contain within them the grate D and the bridge-walls E, the bridge-walls being near the rear of the furnace-chambers in the part Y. a a are watertubes, which extend from the outer sides of the shells B through the furnace-chambers to the crown of the furnace, taking the water from the sides of the boiler to the tops of the furnace-chambers. The furnace chambers are separated by a water-leg, 1), running the whole it ensues that a thorough circulationis established throughout this portion of the boiler. After the heated gases pass the bridge-walls they enter the tines C, said fines being sepa- I rated by a water-leg, c. On the sides of these water-legs water-tubes d, bent to nearly a semicircular form, are fitted in series, as shown,.so I

as to fill a large portion of the flues O and retard the passage of the gases between them, thus imparting their heat to the water, and the water-leg c is made much larger than the water-leg b for the reason that the circulation through tubes (1 commences and ends in said water-leg. Therefore it is requisite that the body of water in the leg should be of suflicient capacity to supply the currents of water risiu g through the tubes d. Near the end of the part X the tines emerge intoan open space or uptake, G, from which the gases are conducted in any convenient manner. I have shown them as passing from this uptake through a horizontal flue, e, to a chimney, H, said chimney being surrounded by a steam drum or jacket, J.

It will be seen that by this improvement I give a very large amount of heating-surface, both shell-surface and tubular, to the action of the fire audits resultant gases, thus securing the desired economy of space, and delay the progress of the gases through the boiler in such a manner as to take from them the greater portion of their heat, thus securing the desired economy of fuel.

There maybe cases in which I should prefer to use the part Y separately from the part X, or to use the part X with a furnace of difiercut construction, in either case produciu g good results but I prefer to use themtogether, as shown. I

-'I claim as my invention-- A boiler having outer shells, A, and inner shells, C, said inner shells inclosin g a furnace and fines, and said 'flues containing within them bent water-tubes cl, emerging from and entering a central water-body, c, substantially as described.

.DAV'ID RENSHAW.

Witnesses CHAS. F. SLEEPER, WM. ZITTEL. 

